Film shrinkage control



jan. 1 6, -1934. `H. w. M ENKE 1,943,687

FILM sRINxAeE coNTRoL Filed May, 1930 Patented Jan. 16, 1.934

PATENT OFFICE FILM SHRINKAGE coN'raoL Harry William Menke, Los Angeles, Calif.,VV assignor to Cinemacolor Corporation, Chicago, Ill., a corporation of Delaware Application May 3, 1930. Serial No. 449,669

7 Claims. (Cl. 91--70) vThis invention relates to a method and apparatus for controlling the shrinkage of photographic nlm generally, and the nlm used for the production of motion pictures, particularly, and 5 has for its object the control of such shrinkage whereby the film may be uniformly reduced to its maximum density.

With the above and other objects in view, as will` be apparent, this invention consists in the l steps and method as well as in the construction, combination and arrangement of parts, all as hereinafter more fully described, claimed and illustrated inthe accompanying drawing, wherein: The g'ure is a substantially vertical section l of an apparatus designed to carry out the present invention.

As is Well known, all nlm, particularly motion picture lm, after being processed in the laboratory, is what is known as green or` uncured;

2Q that is to say, such film contains a much largerreached usually dierent degrees of density and thereforev have shrunk varying percentages due to the varying ages of the respective fllm sections.

This has proven to be objectionable not only in the production of black and pvhite'motion picltures, but it has proven particularly objectionable in the production of motion pictures in.

natural colors. In processes for the production of motion `pictures in natural colors employing two or more images which are to be superposed on the lm, either by the use of a single standard hn or by two separatefhns, lack of registration of these superposed images is very often caused by uneven shrinkage frequently `in vthe same scene and almost always in scenes produced and developed at different times. This'lack of registration due to shrinkage destroys the color values in the projected images and not infrequently results in complete color distortion.

` It has been found that there is acertain point where film shrinks to'its greatest density and that after that point hasbeen reached there is little or no further shrinkage or change in V the illm structure eithery by expansion"'or` by conone hour subject to the heat of 150 F. matic controls may be provided which will regu-'1 -`late the speed of the passage 'of the lm through traction. Heretofore in the production of black and white pictures and in the research incident to the production of motion pictures in vnatural colors, the compensation of or for the shrinkage of the nlm has to some extent been accomplished by mechanical adjustment in eachv printing or projecting machine, but this control or compensation is not constant and to a large extent depends upon the accuracy of each individual machine or skill of the operator.

The present invention is designed to provid method, as well as an apparatus, for controlling this shrinkage of the film, whereby the nlm may be at any time brought to its maximum density. Thus, by the luse of the present method and apparatus, the nlm may be reduced to its maximum density immediately after it has passed through treatment by the laboratory, or at anytime subseqeunt thereto; so that a plurality of film sections treated by the -present method and apparatus will have substantially the same density and shrinkage irrespective of the time at which the treatment takes-place. 'I'he present invention also contemplates not only the uniform reduction vof the nlm to its maxium density but also the maintenance of the nlm in a pliable condition free from brittleness which might otherwise take place by the treatment.

'I'he present invention contemplates the placing of a quantity of lm in an approximately air-tight compartment and subjecting it to the action of heat which will drive the moisture from the lm. At the top of the compartment is provided an exhaust fan whch'will remove the moisture driven from the film by` the action of the heat from the compartment, thereby eliminating any possibility of precipitation. While the film is being so treated for the reduction thereof to its maximum density, it is being constantly sprayed by a solution suitable for maintaining the lm in a pliable condition free from brittleness.

It is to be understood that the lm may pass ,through the compartment or cabinet automatically or manually. It has been found that at a temperature of 150 degrees F. the lm will reach its maximum density in lsubstantially one hour and that it is possible to pass the film through the cabinet or compartment automatically in-such manner that each portion of the film willremain within the cabinet substantially Autothecompartment or cabinet dependent upon the heat maintained in the compartment or cabinet.

','I'he automatic-features of the method and apparatus form no part of the present invention and therefore will not be here described in detail. Reference being had more particularly to the vdrawing 10 designates a substantially-air-tight cabinet having a series of rollers 11 at vor adjoining its top and a series of similar rollers 12 Nat or adjoining 'its bottom. Below the floor of -the inlet opening is a feeding reel 18 while a take-up reel 19 coacts with the outlet opening 17.

It is to be observed that the rollers 11"of one row are staggered with respect to the rollers 12 of the opposite row whereby the filml entering. the cabinet through the opening 16 from the feeding roll 18 may pass alternately over the 'upon the rollers 11--12 within Ithe cabinet l0 will reach its maximum density within substantially one hour` if the heat. therein -is main-l i tained at substantially 150 F. Of course, if

the heat exceeds 150 F. the iilm-must be re moved from the cabinet more quickly and if it falls below 150 F. it mustbe allowed to remain in the cabinet for a greater period of time.`

In order/to maintain the yfilm pliable/during and after its treatment by thepresentprocess, a compression tank 20 is placed at the side of the cabinet 10 and is,connected by a pipe 21 extending vertically upon the interior of the cabinet, with the horizontal spray pipes 22 located respectively at the top and the bottom of'v the cabinet. 'I'he pipe .21 communicates with an auxiliary container 23vin-which is place'dthev solution used for the treatment of the film. By opening the valve 24 of the air tank, the passage of air through the pipe 21 will remove the solution from the container 23 drawing it-into the pipe 2l to force it outwardly through the perforations ofthe spray pipes 22 which direct the sprays so created to and over the body of the film/within the-cabinet 10.

The solution in the container 23v consists of approximately two parts alcohol, four .parts glycerin and one part oil of cedar intimately mixed. This solution when sprayed upon the hn as above described prevents the film from becoming brittle or hard but at the same time does not prevent the lm from reaching its maximum density. It is of course, to be understood that the proportions of the solution above' described may be varied or even the elements changed without departing from the spirit and scope hereof. I

In-the operation of the apparatus heretofore described, a motor 25 isconnected to the take-up wind it upon the take-up rel 19. If the speedV of this motor is such that any given point of 'lmwould take one hour to pass through the cabinet while the temperature therein is 150 F.

the motor may operate continuously at that speed and the lm passing through the cabinet will reach its maximum density. If, however, the temperature rises above 150 F. the speed of the motor 25 should be increased, while if the temperature falls below 150 F. the, speed of the motor should-be reduced. If the temperature, however, is maintained at substantially 150 F. by a suitable thermostatic control the speed-of the motor may remain approximately constant whereby each portion of the lm F will be substantially an hour in passing through the cabinet.

In, order .that only film to be treated will be in the cabinet, the film may be attached to a leader or blank lm which is threaded through the machine and wound upon the take-up'reel until the cabinet is filled with the film to be treated. From the foregoing it is. apparent that a method a-ndoapparatus is produced whichwill bring film to its maximum density without de creasing the pliability or strength of the film.

What is claimed is: 1. The method of controlling the shrinkager of uncured lm consisting in enclosing the film, subjecting it to heat for a time duration sufficient to shrink thelm to its point of greatest density,

while exhausting the air from around the lm and treating the film with a solution capable of maintaining the film pliable.

2. The method of controlling the shrinkage of uncuredvfllm consisting in enclosing the film, exhausting the air from around-the film, subjecting it to approximately 150 F. for substantially one hour whereby the greatest' density of the film lis secured, and simultaneously treating the film to counteract the tendency to become brittle.

3. The method of controlling the shrinkage of film consisting in subjecting the, film for substantially one hour to a dry heat of approximately 150 F. and simultaneously treating the film with a solution of alcohol, glycerine and oil of cedar.v .1

i 5. The method of' controlling the shrinkage of lm consisting in enclosing the film and arranging it in'parallel spaced laps, subjecting vit to a heat of 150 F. for one hour, exhausting the air from around the film, and treating the lm with a solution of alcohol, glycerineand oil of cedar.

6, The Imethod of controlling theshrinkage of uncured lm comprising subjecting the filmto the action of heat fora time period sufficient to shrink the lm to its point of greatest density, andsimultaneously treating the ilmvr to counteract the4 tendency to become brittle.

7. A step in the method of controllingthe shrinkage of uncured film which consists in sub-f jecting the film to the action of heat vfor a. time period sufiicient to shrink the film approximately to its point of greatest density while ,simultaneously removing ai!` from around lthe film.

HARRY 

